Implantable drug infusion devices are well known in the art and are considered to provide patients with prolonged dosage or infusion of a therapeutic agent. Active drug infusion devices feature a pump or metering system to deliver the drug into a patient's system and usually contain electronic pressure sensors and processors. Implantable medical devices that supply ambulatory patients with medication must have a manner of alerting patients to relevant events. Several different alert systems are already used in combination with implantable pumps or other devices, like acoustic or vibration signals.
However, specifically when the infusion device provides with a medication that is essential for the patient and wherein any interruption of said supply would lead to a life threatening event, an efficient alarm system is even more important.
As an example, pulmonary arterial hypertension is a disabling and life threatening disease which, without adequate therapy, has a very poor prognosis quoad vitam. Parenteral prostanoid analogues to date still belong to the most active compounds for the management of this disease. Such therapy must be given lifelong without any interruption. Any treatment interruption could result in hypertensive crisis in the lung circulation which might end up in fatal acute right heart failure. External high precision micropumps serve as technical administration aids which provide permanent subcutaneous or intravenous drug delivery. In order to alert patients when vital drug supply is disrupted, e.g. due to catheter kinking or occlusion, these pump devices are equipped with acoustic occlusion alarms.
External pumps are stigmatising and in the case of a central venous access linked to a substantial risk of catheter infection and sepsis. The latest micropump devices may now be implanted into the subcutaneous space of the right or left lateral lumbar region. These pumps have the advantage of providing well tolerated intravenous drug administration without the risk of infections inherent to external catheters. Monthly refill intervals ensure further patient compliance and convenience. Acoustic alarm systems built into implantable micropumps face numerous technical disadvantages. Acoustic signals which are released underneath the skin are rather silent and may be missed especially during night time. Moreover, acoustic signal sources require a battery which may wear out rapidly, if the occlusion could not be removed within a short time. Batteries would also wear off, if repeated alarm situations did occur. Thus an implanted pump device which per se should last for close to 10 years might have to be replaced due to alarm battery failure after just some days.
In practice, even more important is that an alarm poses a sole awareness measure without resolving the possibly fatal consequences of the stopping of a prostanoid delivery. If such an alarm happened, e.g., when travelling abroad, then there might be no infrastructure available to solve this sudden life threatening treatment halt.
US2009/0076485A1 describes a safety system for implantable pumps with two catheters, which is unprotectedly exposed to the patient's tissue. Thus the emergency outlet of the second back up catheter may within a short period be encapsulated and occluded by a connective tissue capsule which is built by the body's system and thereby rendered ineffective.
US2003/216683A1 describes a delivery device for metered drug delivery comprising an electronic pressure measurement system and a controller that selectively opens the valves to steadily release a defined quantity of a liquid medicament.
WO2008/106810A1 discloses a hydraulic occlusion detection system integrated in a medical device.
US2012/0078181A1 describes infusion pumps with a cartridge body with a reservoir and an outlet port and a manifold connected to said body, having a through-bore in fluid communications with said outlet port.
Thus, there is still an unmet need to provide an emergency system that makes sure that the patient gets aware of said malfunction as soon as possible and wherein constant supply of the medication is still provided even when the regular supply systems are disturbed.